Portable refrigerator



FIG. 1 is a front perspective view of a portable refrigerator showing my/our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The contrast in shading between the top and bottom portions relative to the central portion represents a contrast in appearance only and does not represent any particular color, material, texture, or finish. The broken lines depicting the remainder of portable refrigerator form no part of the claimed design. 

CLAIM The ornamental design for a portable refrigerator, as shown and described. 